Thickened inorganic oxidizer salt slurried explosive containing tris(hydroxymethyl)-nitromethaneand air-entrapping material



3,409,485 THICKENED INORGANIC OXIDIZER SALT SLURRIED EXPLOSIVE CONTAINING TRIS(I-IYDROXYMETHYL)-NITROMETH- ANEANDAIR-ENTRAPPINGMATERIAL Joseph J. Minnick, Marion, Ill., assignor to Commercial Solvents Corporation, New York, N.Y., a corporation of Maryland No Drawing. Filed Sept. 15, 1967, Ser. No. 668,194 11 Claims. (Cl. 149-21) ABSTRACT OF THE DISCLOSURE Thickened slurry explosive compositions containing an inorganic nitrate oxidizing salt, tris (hydroxymethyl)- nitromethane, water, as sensitizer a non-explosive, fine-lydivided, air-entrapping material, and a thickening agent. These explosive compositions are useful in small bore hole blasting operations.

SUMMARY OF THE INVENTION This invention relates to thickened slurry explosive compositions comprising an inorganic nitrate oxidizing salt, tris(hydroxymethyl)nitromethane, water, as sensitizer a non-explosive, finelydivided, air-entrapping material, and thickening agent. In a particular aspect, this invention relates to thickened slurry explosive compositions having high rates of detonation and suitable for use in small bore hole blasting operations, said composition containing an inorganic nitrate oxidizing salt, tris(hydroxymethyl)nitromethane, water, thickening agent, and as sensitizer a non-explosive, finely-divided, air-entrapping material. The use in explosive compositions of inorganic nitrate salts, such as the alkali metal nitrate, the alkaline earth metal nitrates, and in particular ammonium nitrate, has become widespread in the mining and quarrying arts. For example, thickened aqueous slurries containing ammonium nitrate have found extensive use in many blasting operations. Explosive compositions containing ammonium nitrate and nitroparafiins are also known to the art and have a wide variety of applications.

Even though explosive compositions such as those described above have proven effective for numerous uses, such explosives are generally not suitable for use in small bore hole explosive applications unless sensitized -by a sensitizer which is itself a high explosive, such as for example trinitrotoluene (TNT). The principal reason for this is that without the employment of a high explosive sensitizer the detonation velocities of such compositions are not sufiiciently high to give the desired results. For reasons of economy and, more importantly, for reasons of safety, it is desirable to avoid the use of high explosive sensitizers in ammonium nitrate containing explosive compositions.

It is an object of the present invention to provide thickened explosive compositions containing an inorganic nitrate oxidizing salt, tris(hydroxymethyl)nitromethane, water, a thickening agent, and a non-explosive sensitizer.

It is a further object of the present invention to provide thickened slurry explosive compositions containing an inorganic nitrate oxidizing salt, tris(hydroxymethyl)nitro- United States Patent methane, water, a thickening agent, and a nonexplosive sensitizer which have high rates of detonation and are suitable for use in small bore hole blasting operations.

Other objects and advantages of the present invention will be apparent from the specification and appended claims.

The present invention resides in the discovery that explosive compositions having high rates of detonation and suitable for use in small bore hole blasting operations are prepared by forming an admixture of from about 10 to about 90% by weight of an inorganic nitrate oxidizing salt, from about 5 to about by weight of Water, from about 5 to about 50% by weight of tris(hydroxymethyl)- nitromethane, a thickening agent, and a sensitizing amount of a non-explosive, finely-divided, air-entrapping material, the said weights being based on the total of the weights of the nitrate salt, the water, and the tris(hydr0xymethyl)- nitromethane.

The detonation rate of an explosive composition is the rate at which the detonation front passes through the explosive material. Detonation rate is typically expressed in feet per second. For the purpose of the present invention, high detonation rates are generally considered to be in excess of 14,000 feet per second. The compositions of the present invention have detonation rates in excess of 14,000 feet per second, with detonation rates in excess of 16,000 feet per second being reasonably common.

Detailed description The tris(hydroxymethyl)nitromethane is employed in the compositions of the present invention in an amount in the range of from about 5 to about 50%, with an amount in the range of from about 5 to about 30% being preferred.

Any suitable inorganic nitrate oxidizing salt or mixtures of two or more salts may be employed in the compositions of the present invention. Examples of such salts include ammonium nitrate and sodium nitrate, with ammonium nitrate \being preferred. The form and particle size of ammonium nitrate (or other salt) are not critical features of the present invention. For example, low density and high density ammonium nitrate prills as well as ground or granular ammonium nitrate may be employed. Preferably, the particle size of the salt is sufficiently small to pass a 20 mesh screen.

As previously indicated, the inorganic nitrate salt is employed in an amount in the range of from about 10 to about with an amount in excess of 40% being preferred.

The water content of the compositions of the present invention is such as to dissolve all or a portion of the inorganic nitrate salt. Water is employed in the compositions in an amount in the range of from about 5 to about 50%, with an amount in the range of from about 5 to about 30% being preferred.

The sensitizers employed in the compositions of the present invention are non-explosive, finely-divided, airentrapping materials. Examples of such sensitizers include resin balloons, bagasse, wood flour, cork, balsa, and the like. Resin balloons of use as sensitizers in the compositions of the present invention are water-insoluble, thinwalled, hollow, spherical balloons of a polymerized thermosetting resin selected from the group consisting of urea 4 formaldehyde and phenol formaldehyde. Such resin balof particle size sufliciently small to pass a 20 mesh screen, loons are commercially available and are more fully dewas employed. Detonation was accomplished with 'onescribed in US. Patent 3,101,288 to Coursen et a1., issued half pound Composition B boosters. In the table all parts August 20, 1963. are by weight.

TABLE I Composition A B C Ammonium Nitrate er Resin balloons (phenol formaldehyde) 2. Bagasse Tris(hydroxymethyl) nitromethane 15. H 2 Guar gum 0.8 Nitromethane 2-nitropropane Detonation velocity-teet/second.

MOO)

The above formulations were prepared as follows: The

The amount of non-explosive sensitizer required to sensitize the compositions of the present invention will vary tris(hydroxymethyl)nitromethane and water were placed and will depend, among other things, upon the particular in a mixing machine and the mixer was operated until'a sensitizer employed and the degree of sensitization re. solution was formed. The ammonium nitrate, jsensitizer, quired. Generally, an amount in the range of from about and guar gum were then individually added to the solu- 0.1 to about 6.0% by weight is suitably employed, with tion under mixing. Mixing was then continued until a amounts in the range of from about 0.4 to about 3.0% composition of substantially uniform viscosity was obbeing preferred, the weights based on the total weight of tained. The mixing procedure was carried out at room the total composition. 0 temperature.

The class of materials used as thickeners for aqueous inorganic nitrate oxidizing salt explosive compositions is Explosive compositions similar to those of Example 1 known and is illustrated by such materials as guar gum, are Shown inTable IL gum Arabic, pregellatinized starch and carboxymethyl cellulose, with guar gum being preferred. The amount of Example 2 TABLE II thickening agent employed in the composition of the pres- Com osition H I ent invention will, of course, depend upon the particular Sodium 624 m0 thickening agent and the viscosity desired for the particug 15-0 15.0

lar composition. An amount of thickening agent in the 5333 I 13 :12 range of from about 0.5 to about 5.0% by weight based my y t tha 18.4 10.8

on the weight of the total composition is typically em- 0 I 1 Since many embodiments of this invention may be The compositions of the present invention may opn sincefllany changes F x q e in tionally contain, for example, a metal powder, such as bodlmeqts descnbedr P 15 to be i p q as aluminum, to enhance their power, a carbonaceous ma- Illustrative only and the mventlon 1S defined by clalms terial, such as fuel oil, to provide oxygen balance when appendefi1 f' required, and a nitroparaffin other than tris(hydroxy- What Is Planned I methyl)nitromethane, such as nitromethane, to obtain A thlckened slurry exploslve m eompns' higher brisance. my I The compositions of the present invention are prepared (a) about 901% by welght of an by known mixing procedures. The tris(hydroxymethyl) game filtrate oxldlzlng salt nitromethane is soluble in water and, if desired, may first (b) m about about by welght of F be dissolved in water before mixing with other ingredients. dwxymethynmimmethane, p The compositions may be safely manufactured, stored (e) from about about 5 by Q of e and shipped and hence may be prepared in a processing PP Q finely'dlvlded alr'entrappmg. i plant and transported to the blasting site. If desired, the 50 smzulg matenal seleeted the group eonsxstmg compositions may also be prepared at the site. of thm'waned hollow, sPhePcal balloons i The compositions of the present invention are resistant 5 balsa m amounts sufliclent to to water, making them useful in wet as well as dry holes. sensltlee eomposltion The compositions require no container even in wet holes. (e) a thlekenmg agent m amunts summnt to thicken They displace water and maintain their integrity without the P l 1 dilution for extended periods of time before detonation. Bald i bemg based I.1thette1efthe welghts The compositions have a density in excess of 1.0 and beof the filtrate Salt the msmydroxymethyl) cause of this high density possess high bulk strength. il the F I v The compositions of the present invention are detonated h .9f 9 clalin 1 Wherem the morgame in the known manner by conventional booster systems, mtrate oxldlzmg a i 1S m l such as for example Pentolite, Composition B, RDX, and PP P P of F am. 1 wherem the Inorganic the like. The amount of booster is determined in accordnitrate oxlelzmg e fmtrate' ance with well known practice in the use of the particular comp F 9 9 elalm wherem the ammomum booster chosen nitrate is of a particle size sufiiciently small to substantial- The invention will be understood more fully by refer- 1y pass a 20 mesh fi ence to the following specific examples. It is understood The eomposmon of elalm 1 wherem the amount of that the examples are presented for the purpose of illuswater is in the 1 of frm.about 5 to tration only and are not intended as a limitation of the The camposltlonof clam 1 Wh-erem the amount of tris(hydroxymethyl)nitromethane IS in the range of from invention.

Example 1 about 5 to about 30% 7. The composition of claim 1 wherein the amount of A series of runs was conducted in which the detonation inorganic nitrate oxidizing salt is in the range of from velocities of thickened slurry explosive compositions havabout 40 to about ing ingredients in the parts by weight indicated in Table I 8. The composition of claim 1 wherein the amount of were determined. In the runs ground ammonium nitrate 7 sensitizing material is in the range of from about 0.1 to

about 6.0% by weight based on the weight of the total 6 References Cited UNITED STATES PATENTS 3,161,551 12/1964 Egly et al 14947 X 3,275,485 9/1966 Egly 149-89 3,301,724 1/1967 Scott 14989 X 3,338,165 8/1967 Minnick 14989 X BENJAMIN R. PADGETT, Primary Examiner.

11. The composition of claim 1 wherein the thickening 10 S. J. LECHERT, JR., Assistant Examiner.

agent is guar gum. 

